According to a configuration shown in FIGS. 1 and 2, an aircraft 10 comprises multiple engine assemblies 12 positioned beneath the wing 14. As shown in FIG. 2, an engine assembly 12 comprises:                an engine 16 in which flows a core air flow,        a nacelle 18 positioned around the engine 16 so as to delimit, with the latter, an annular duct in which flows a bypass flow of cold air, and        a pylon 20 which provides the connection between the engine 16 and the wing 14.        
The pylon 20 comprises a rigid primary structure 22 which, among other things, serves to transmit forces between the engine 16 and the rest of the aircraft 10, and a secondary structure 24 which encloses the primary structure 22 and reduces the drag of the pylon 20.
As shown in FIGS. 2 and 3, each engine assembly 12 comprises at least one heat exchange device 26 configured to cool hot air which is taken from the compression stages of the engine 16 and is destined for the systems for air-conditioning and pressurization of the aircraft, and/or for de-icing of the wing. According to one embodiment, each heat exchange device 26 comprises:                a heat exchanger 28 which is parallelepipedal in shape and which has a first hot air circuit connecting a first inlet 30 and a first outlet 32, and a second cold air circuit connecting a second inlet 34 and a second outlet 36,        a hot air supply duct 38 which is configured to take hot air from the engine 16 and is connected to the first inlet 30,        a hot air outlet duct 40 connected to the first outlet 32,        a cold air supply duct 42 which is configured to take cold air from the bypass flow and is connected to the second inlet 34,        an exhaust duct 44 which is configured to eject air outside the aircraft and is connected to the second outlet 36.        
In order to regulate the temperature of the hot air, the heat exchange device 26 comprises a regulating system 46 that is configured to adjust the flow rate of the cold air and is positioned upstream of the heat exchanger 28, at the cold air supply duct 42.
This regulating system 46 comprises:
                an obturator (not shown) which is positioned inside the cold air supply duct 42 and is mobile in rotation about a transverse pivot axis (which extends across a diameter of the cold air supply duct 42), between a closed position in which it blocks the cold air supply duct 42 and more- or less-open positions in which it allows a flow of air with a lower or higher flow rate to flow in the cold air supply duct 42,        an actuator 48 which is configured to control the position of the obturator and which comprises an output shaft 50 coupled to the pivot axis of the obturator.        
The heat exchanger 28 and the regulating system 46 are positioned in a region located above the primary structure 22 and beneath the secondary structure 24 of the pylon.
The obturator must be positioned at a portion of the cold air supply duct 42 of essentially constant cross section so as to allow it to pivot. Therefore, the obturator is remote from the heat exchanger 28, which tends to increase the space required for the heat exchange device.
The actuator 48 and its output shaft 50 are positioned along a direction perpendicular to the direction of the cold air supply duct 42, which also tends to increase the space required for the heat exchange device.
However, aircraft engines have ever larger diameters and are positioned as close as possible to the wing in order to improve aerodynamic performance and to maintain a minimum ground clearance. Consequently, the region located above the primary structure 22 and beneath the secondary structure 24 of the pylon is evermore restricted, which tends to complicate the integration of the heat exchange device.
The disclosure herein aims to remedy some or all of the drawbacks of the prior art.